Re-usable ink-releasing elements and process of making



June 5, 1962 D. A. NEWMAN ETAL 3,037,879

RE-USABLE INK-RELEASING ELEMENTS AND PROCESS OF MAKING Filed Sept. 24, 1959 RESINOUS INK-EELEASING LAYE-E.

PI As-IIc FILM FOUNDATION EESINOUS INI RELEAsINe- LAYER PLASTIC BINDER LAYER FLEX IBLE FOUNDATIO N EESINOUS VOLATILE OILY IMAGING BI NDER SOLVENT MATERIAL- MATEIZlA-L.

MIX TO UNIFORM CON5| STENCY SPREAD EVENI-Y ON $FRE'AD EVENLY s-nc BINDER ON As Ic; LAYER ON ANY FILM FOUNDATIQN FLEXIBLE FOUNDATION EVAPORATE SOLVENT NoN- $TE'N cI I I ING RE-USABLE. INK- RELEA5ING TRANSFER ELEMENT INVENTORS Douylaa A Ne wmarz BY Allan T Sc /7/0lz/7aucr' Mama ATTORNEYS United States Patent 3,037,879 RE=USABLE INK-RELEASES ELEMENTS AND PROCESS OF MAKING Douglas A. Newman, Glen Cove, and Allan T. Sehlotzhauer, Locust Valley, N.Y., assignors to Columbia Ribban and (Iarbon Manufacturing (10., Inc, Glen Cove,

N.Y., a corporation of New York Filed Sept. 24, 1959, Ser. No. 341,931 14 Claims. (Cl. 117-361) This invention relates to novel ink-releasing sheets and ribbons and the method of producing them.

This application is acontinuation-in-part of our application Serial No. 503,830, filed April 25, 1955, now abandoned, which in turn is a continuation of our application Serial No. 374,814, filed August 17, 1953, and issued as US. Patent No. 2,820,717 on January 21, 1958.

The aforementioned applications disclose novel resinous ink compositions which when applied to a paper foundation and allowed to set result in the formation of a porous, spongy, resinous, non-transferable layer containing within its pores a pressure-transferable liquid ink composition.

Up to the present it was known to prepare transfer sheets and typewriter ribbons of the carbon or 'hectograph type employing as the foundation sheet a thin film of synthetic plastic material such as cellophane or cellulose acetate or other synthetic film and an imaging layer of pigment or dye and wax. Such sheets and ribbons found great utility due to their flexibility, resilience and appearance but have the serious drawback of being able to be used only once. Due to the smooth surface and lack of tooth of such films the imaging layer containing pigment or dye and wax transfers completely in what is known as a stenciling manner leaving the bare film exposed. Thus, in the case of typewriter ribbons, for instance, upon re-use there is no imaging material remaining on the workable portion of the ribbon and it must be discarded.

As can readily be seen, it would be of the greatest advantage to produce a typewriter ribbon or transfer sheet which has the beneficial properties of resilience, flex strength and smooth appearance and yet which is nonstenciling and thus may be re-used time and time again Without any appreciable loss of imaging strength.

The difliculties have been overcome and the many problems arising from these somewhat contradictory requirements are met by the present invention.

Plastic films are known which have excellent appearance, strength and resilience but their use as foundations in the transfer sheet art has been limited due to the fact that these plastic foundations have such a smooth surface as to provide substantially no tooth or adhesion for the imaging layer. The result is that the imaging layer transfers under pressure substantially completely in what is known as a stenciling manner. Thus the transfer sheets can be used only once and are for this reason relatively expensive and burdensome.

It is an object of the present invention therefore to prepare non-stenciling ink-releasing sheets and ribbons which have a plastic film foundation and yet may be re-used many times with no appreciable loss in tone strength.

It is another object of the present invention to prepare ink-releasing plastic foundation sheets of the carbon type with which more than clear copies may be made over the same area, and yet which are smudge-proof and clean to the touch.

It is a further object of the present invention to prepare re-usable ink-releasing sheets and ribbons of greater strength and resilience than those known up to the present. r

These and other objects are accomplished by applying the resinous ink compositions of the aforesaid applica- Patented June 5, 1962 tions and as described hereinafter to a plastic film foundation and allowing them to set and leave a porous, spongy, substantially non-transferable resinous ink carrier coated over the plastic film foundation. The ink is carried in liquid form together with a non-volatile component which is a non-solvent for the spongy resin within the pores of the resin.

Upon the application of pressure to the back of the present ink-releasing plastic foundation sheets or ribbons caused by a pen, pencil, stylus, type bar or the like, an amount of the ink is released from the spongy resin and oozes onto the copy sheet. At the same time, apparently by capillary action, the vacated pores of the sheet or ribbon are regenerated with more liquid ink from the nonimpressed areas. The capillary action serves two functions. In the first place, it tends to hold the imaging material beneath the surface of the porous resin, thus providing a surface which is clean to the touch. Secondly, it serves to rush surplus imaging material to the impressed areas so that the sheet or ribbon may be re-used time and time again without any appreciable loss in tone strength.

One of the most critical features of the present manifolding system is the discovery of a pigment supplying layer which will not release from a plastic film foundation under pressure. Such idea is novel in and of itself.

In the drawing:

FIGURES 1 and 2 are diagrammatic cross-sections, to,

an enlarged scale, of transfer elements according to the present invention. The element of FIG. 1 comprises a film foundation of plastic material which is at least partly soluble in the volatile solvent used to apply the resinous ink-releasing layer. The element of FIG. 2 comprises any flexible foundation such as paper or plastic film which carries a binder layer of plastic material which is at least partly soluble in the volatile solvent used to apply the resinous ink-releasing layer.

FIG. 3 is a flow sheet illustrating alternative processes for preparing the transfer elements of FIGS. 1 and 2. The components of the ink-releasing layer are mixed to a uniform coating consistency. They are then spread evenly as a thin layer over either a plastic film foundation or over a plastic binder layer which is carried by a suitable flexible foundation. In either case the plastic film or binder layer comprises a plastic which is at least partly soluble in the volatile solvent of the applied ink-releasing layer. Next the volatile solvent is evaporated to form the novel transfer elements of the present invention.

In accordance with the present invention, any desired plastic film foundation may be employed such as cellophane, cellulose esters such as cellulose acetate and cellulose triacetate; hydrocarbon polymers such as polyethylene and polypropylene; unsaturated polymers such as polystyrene, polyvinyl fluoride, commercially available under the name Teslar, polyvinyl chloride, polyvinylidene chloride, commercially available under the name Saran, polyvinyl acetate, vinyl chloride-vinyl acetate copolymers of the Vinylite series such as Vinylite VYHH; polyester res-ins such as polyethylene terephthalate, commercially available under the name Mylar, as well as many others.

The surface of these films may be frosted in any known to curling, cut-through, etc. Other polymers having good strength qualities found particularly useful in the preparation of typewriter ribbons include cellulose acetate, oriented polyethylene, oriented polypropylene, oriented styrene and polyvinyl fluoride (Teslar). I As the resinousink carrier which sets to a porous, spongy layer, unsaturated polymers such as polyvinyl chloride, polyvinyl fluoride, polyvinyl acetate, vinyl chloride-vinyl acetate copolyrners of the Vinylite series such as Vinylite VYHH and VYLF, polyvinyl butyral, polyacrylic acid, polystyrene, polyvinylidene chloride (Saran), and others; hydrocarbon polymers such as polyethylene and polypropylene; polyurethanes obtained by reacting an isocyanate such as toluene di-isocyanate with a hydroxyl-containing compound such as an alkyd resin or a glycol; polyamides such as alcohol-soluble nylon, a well as many others, may be used.

No particular criticality exists inthe selection of the pore-forming material but soft vinyl chloride-vinyl acetate copolymers such as Vinylite VYHH are particularly well suited because of their softness,.flex strength and excellent adherence for the underlying film.

The pore-forming layer may be applied to the'filrn base in any desired manner; In the preferred embodiment, the resinous pore-forming material together with the non-volatile, non-solvent component and pigment or dye are dissolved in a suitable solvent such as a 3:1 mixture of ethyl acetate and toluol and the mixture ground to a suitablecoating viscosity. The mixture is then spread evenly over the plastic film base by suitable coating apparatus and allowed to cool and harden by evaporation of the volatile ingredients to form a smooth, pressure-transferable ink-releasing sheet or ribhem of the type disclosed. It has been found advantageous to heat the final sheet or ribbon for a short time to a temperature of 150 C. or above to fusethe layers and provide a smudge-free product.

in .the selection of a material suitable as the nonvolatile component one critical requirement rnust be observed. Such material must be a non-solvent for the resinous pore-forming material. In general, non-volatile mineral, vegetable and animal oils are found most satisfatcory, such as naphthenic mineral oil, neats-foot oil, refined rapeseed oil, cottonseed oil, peanut oil, castor oil, olive oil, sperm oil, etc. Materials such as butyl stearate, lanolin, petrolatum and hydrogenated vegetable oils such ascottonseed oil have been used successfully, particularly in admixture. with the above-named. oils. 'It has been found that when a mixture of an oil such as mineral or vegetable and a material from the group of lanolin, petrolatum and hydrogenated vegetable oil is used as the nonvolatile component, the final product has excellent properties of stability for long periods of time in that the nonvolatile component is semi-solid and substantially nonflowing at room temperature. The oil does not tend to leach out to the surface of the sheet and stain sheets in casual contact therewith. Fatty acids and esters may also be used, such as oleic acid, isopropyl palmitate, diglycol laurate and diglycol oleate. V

In another embodiment of the present invention, the resinous pore-forming material may be compounded and applied using small amounts of volatile components. For instance, the resinous material such as Vinylite VYHH or VYNC may be suspended as a finely divided dispersion in an organic liquid vehicle containing minor amounts of a volatile dispersing liquid, in which case the dispersion is called an organosol. Such dispersions may be compounded in any conventional manner and are described by Schildknecht in Vinyl and Related Polymers (1952) at page 434 and following. Such dispersions contain a plasticizer such as di-(Z-ethylhexyl) phthalate, dioctyl sebacate and dibutoxyethyl phthalate which act as dispersing agents at room temperatures and keep the resin at a coatable consistency and which act as solvents at eleusing volatile solvents. This is important in cases where it is desired to avoid the hazards of using large amounts of volatile solvents.

In still another embodiment it has been found par ticularly useful to employ a binding layer between the plastic foundation film and the'spongy o-verlayer to effect improved adhesiveness and to counteract stenc-iling tendencic-s where the present ink-releasing elements are used for heavy duty work. The use of such binding layer has been found quite advantageous, for instance, in cases where a heavier-than-normal pressure is exerted in order to produce many copies at one time. It has been found, for instance, that where the foundation sheet is Mylar and the spongy overlayer is Vinylite VYHH, an increased attraction of the overlayer for the foundation may be effected by first coating the Mylar with a thin, homogeneous, continuous layer of Vinylite VYHH which contains no incompatible non-volatile component. Then when a solvent mixture of the spongy overlayer is applied, the solvent parti-ally attacks the binding layer because of its mutual solubility and a strong bond results. Thus, as the component of the binding layer, a homogeneous, continuous film of any of the materials used as the components of the pore-forming layer mentioned prior may be used in the absence of any incompatible non-volatile materials.

Conventional imaging materials which are used in the preparation of carbon papens, typewriter ribbons or hectograph sheets and in the imaging of planographic printing plates may be employed herein. For some reason, it has been found that where the pigment employed is blue pigment, then the porous, ink-releasing layer is bonded more strongly to the film foundation, in the absence of a binding layer, than is the case where a carbon black pigment is used. This appears to be due to the fact that blue pigment is of relatively tiny particle size and forms a bluish coating whereas carbon black has a larger particle size and results in a greater pigment load on the ink-releasing element. Where the sheet is to be used for imaging planographic plates, compositions such as nigrosine black and Bismarck brown are used.

' it has been found quite advantageous in the case where the pore-forming material is applied dissolved in a solvent that the plastic film foundation also be at least partly soluble in the same solvent. It appears that the solvent,

, prior to evaporation, attacks the surface of the foundation film leaving it pitted or frosted. Thus the porous material grip on the foundation sheet and cannot be stenciled olf. Very good results have been obtained, for instance, where the plastic film foundation and the pore-forming material are composed of the same plastic material. This is the case where the pore-forming material of Examples I and II following are applied to a continuous, homogeneous film foundation of Vinylite VYHH; those of Examples III and IV are applied to a homogeneous, continuous film foundation of Vinylite XYSG; those of Examples V and VI are applied to a homogeneous, continuous film foundation of Vinylite AYAF; and so on.

The following examples are set forth as merely exemplary and should not be construed as limitative.

As a guide to suitably selecting the proper proportions, it must be indicated that in most cases they will lie within the ranges'indicated by the following table.

Parts by weight Amount suflicient to render the mixture readily coatable. Usually between 45 and 120.

The following examples illustrate the preparation of resinous pore-forming compositions which were solventapplied over films of polyethylene terephthalate (Mylar), Vinyli'te VYHH and polyvinyl chloride, each having a thickness of 0.5 mil and allowed to set by evaporation of the solvent.

These compositions are applied in such amounts that, upon evaporation of the solvent, there remains about from 1.5 oz. per 20" X 30" X 500 sheets to about 24 oz. per 20" x 30 X 500 sheets. Stated differently, in terms of a 1 inch ribbon, the range of coating can vary from about 0.06 oz. per 1000 feet to about 1 oz. per 1000 feet. It should be understood, however, that variations in these amounts may be made Where the need dictates.

Example I Ingredients: Pants by weight Solid base, soft vinyl chloride-acetate copolymer (Vinylite VYHH) 85-88% vinyl chlo- Solid base, polyvinyl butyral (V inylite XYSG) Non-volatile, non-drying softener- Lanolin 14.4

Mineral oil 11.8 Coloring matter, alkali blue 11.7 Volatile solvents Toluol 30.6 Ethyl acetate 86 Example IV Ingredients:

Solid base, polyvinyl outyral (Vinylite XYSG) 10 Non-volatile, non-drying softener Mineral oil 5.5

Butyl stearate 10.5 Coloring matter Carbon black 4.2

Alkali blue 3.1 Volatile solvents Toluol 23.6

Ethyl acetateu 93 6 Example V Ingredients:

Solid base, polyvinyl acetate (Vinylite AYAF) 10 Non-volatile, non-drying softener Lanolin 4.4 Mineral oil 3.7 Coloring matter, alkali blue 5 Volatile solvents Toluol 7.1 Ethyl acetate 46.5

Example VI Ingredients:

Solid base, polyvinyl acetate (Vinylite AYAF) 10 Non-volatile, non-drying softener, fatty acid,

i.e. oleic acid 1O Coloring matter-- Carbon black 1.8 Alkali blue 1.3 Volatile solvents Toluol 6.8 Ethyl acetate 46.7

Example VII Ingredients:

Solid base, soft vinyl chloride-acetate copolymer (Vinylite VYHH) 10 Non-volatile, non-drying softener Petrolatum 10 Refined rapeseed oil 8.3 Coloring matter, alkali blue 8.3 Volatile solvents Toluol 15 Ethyl acetate 52 Example VIII Ingredients Solid base, soft vinyl chloride-acetate copolyrner (Vinylite VYHH) 10 Non-volatile, non-drying softener- Hydrogenated cottonseed oil 10 Mineral oil 8.3 Coloring matter, alkali blue 8.3 Volatile solvents Toluol 15 Ethyl acetate 52 Example IX Ingredients Solid base, soft vinyl chloride-acetate copolymer (Vinylite VYHH) 1O Non-volatile, non-drying softener, lanolin 22 Coloring matter- Carbon black 2.9 Alkali blue 2.1 Volatile solvents Toluol 13.8 Ethyl acetate 54.4

The preceding examples show the use of polymers applied by solvent coating to Mylar, Vinylite VYHI-I and polyvinyl chloride foundations respectively in the following manner.

The polymer, softeners and coloring matter are ground together, e.g. in a warm ball mill, until a smooth, uniform consistency is reached. Other colors may be added or substituted as desired, either dry or in oil suspension, to intensify the color or change the hue.

The alkali blue, carbon black, or other coloring matters or pigments are preferably first dispersed in at least an equal weight of the mineral oil or other non-volatile, non-drying softener to simplify their addition to the mixture, this softener of course being included in computing the total amount permissible in the mixture as above indicated.

The volatile ingredients which may be any suitable solvents for the polymer andsoftener are then added in spar/ere an amount sufficient to give a composition having suitable viscosity for coating at room temperature, and ground with themixture fo a uniform consistency. The mixture is then spread evenly on the foundation film by suitable coating apparatus and allowed to cool and to harden by evaporation of the volatile ingredients to form a smooth pressure-transferable carbon coating having the properties described in detail heretofore.

As presently understood, the softening ingredients, which are non-solvents for or non-miscible with the polymer carrier, are uniformly distributed throughout the polymer composition, and when the composition is coated upon the Mylar, Vinylite VYHH or polyvinyl chloride foundations and the volatile components are evaporated, the softening ingredients form a discontinuous phase Within the polymer, thereby forming a cellular or spongelike film. The coloring matter added to the composition appears to be distributed through the solidified film primarily, although probably not entirely, in the discontinuous phase.

Thus, when an imaging pressure is applied on Mylar, Vinylite' VYHH or polyvinyl chloride ribbons or inkreleasing sheets coated with the above compositions, as for instance by a stylus, pencil, type bar or other'inscribing apparatus, the film of porous polymer releases the softeners and coloring matter in image form to an adjacent copy paper sheet. Accordingly, it may be seen that the non-volatile, non-drying softeners function not only to modify the consistency of the polymer and render the latter suitable as a binder for a pressure-transferable carbon paper coating, but in addition they also function as primary color-carrying vehicles in the coating.

It should be understood that any of the aforementioned pore-forming materials may be substituted for any of the polymers of the above examples with slight variations being made with respect to the solvents and non-volatile components used depending upon the solubility of the pore-forming material and the solubility of the plastic film foundation. Also, where desired, the film foundation may first be coated with an adhesive binding layer consisting of a homogeneous, continuous film of any of the resinous materials used in the pore-forming layer, but in the absence of incompatible, non-volatile components; This provides an underlayer which may be attacked by the solvent of the pore-forming layer in the aforesaid manner.

In the manufacture ofink-releasing sheets and ribbons according to this invention, various solvents, oils and coloring materials may be used, the essential point of the invention being the discovery that when poreforming polymers are used as thecarrier for the carbon ink or hectograph dye, so that the resulting pressuretransferable imaging layers are significantly more heat and smudge-resistant than corresponding wax-base layers, and said porous carrier is coated on a plastic film foundation, there results a sheet or ribbon which may be re-used many times more than conventional wax-base transfer sheets or ribbons even though the foundation sheet has a smooth plastic surface and complete transfer in a stenciling manner would be expected.

Variations and modifications may be made Within the scope of the claims and portions of the improvements may be used without others.

Weclaim: V

1. Process of'preparing non-stenciling, re-usable pressure-sensitive ink-releasing elements which comprises coating a flexible foundation with an overlayer of a continuous plastic film as an adhesive middle layer to form the Working surface of said foundation, and overcoating said middle layer with a top layer of resinous composition comprising a resin, a non-volatile component which is a non-solvent for the resin, a volatile component which is a solvent for said resin and at least a partial solvent for the plastic of said middle layer, and a quantity of imaging material, and allowing said volatile component to evaporate whereby is formed a porous, spongy, inkreleasing element, said top' layer being firmly bonded to the Working surface of said foundation due to a partial dissolving thereof by the volatile solvent prior to evaporation.

2. Process of preparing non-stenciling, re-usable pressure-sensitive ink-releasing elements according to claim 1 in which the flexible foundation is polyethylene terephthalate, the adhesive middle layer comprises vinyl chloride-vinyl acetate copolymer, and the top layer comprises vinyl chloride-vinyl acetate copolymer.

3. Process of preparing non-stenciling, re-usable pressure-sensitive ink-releasing elements which comprises coating 21 plastic film foundation on its working surface with a layer of resinous ink composition comprising a resin, a non-volatile component which is a non-solvent for said resin, a quantity of imaging material and a volatile solvent for said resin which is also at least a partial solvent for the working surface of said foundation, and allowing said layer to set by evaporation of said solvent whereby is formed as the continuous phase a porous, substantially nonpressure-transferable layer of said resin firmly bonded to the working surface of said foundation and containing as the discontinuous phase a pressuretransferable mixture of said non-volatile component and said imaging material. 4. Process according to claim 3 wherein the plastic film foundation consists of a plastic film which is at least partially soluble in the volatile solvent of the resinous ink composition.

5. Process according to claim 3 wherein the plastic film foundation consists of polyethylene terephthalate bearing a'layer of synthetic resin which is at least partially soluble in the volatile solvent of the resinous ink composition and which forms the working surface of said foundation.

6. Process according to claim 3 in which the resinous ink composition comprises 10 parts by weight of vinyl resin, from 7.5 to parts by weight of non-volatile component, from 3 to 75 parts by Weight of imaging material and from to 120 parts by weight of volatile solvent.

7. A non-stenciling, re-usable pressure-sensitive inkreleasing element comprising a plastic film foundation having an ink layer bound to the working surface thereof, said ink layer comprising the residue of a coating composition comprising a resin, a non-volatile component which is a non-solvent for said resin, imaging material and a volatile solvent for said resin which is also at least a partial solvent for the working surface of said foundation, after evaporation of said solvent, said ink layer comprising as the continuous phase a porous, substantially non-pressure-transferable layer of said resin and containing as the discontinuous phase a pressuretransferable mixture of said non-volatile component and said imaging material, said ink layer being firmly bonded to the working surface of said foundation due to a partialdissolving thereof by the volatile solvent prior to evaporation.

8. A non-stenciling, re-usable pressure-sensitive ink releasing element according to claim 7 wherein the plastic film foundation consists of a plastic film which is at least partially soluble in the volatile solvent of the resinous ink composition.

9. A non-stencilin-g, re-usable pressure-sensitive ink-releasing'element according to claim 7 wherein the plastic film foundation consists of polyethylene terephthalate bearing a layer of synthetic resin which is at least partially soluble in the volatile solvent of the resinous ink composition and which forms the working surface of said foundation.

10. A non-stenciling, re-usable pressure-sensitive inkreleasing element according to claim 7 wherein the coating composition comprises 10 parts by Weight of vinyl resin, from 7.5 to 35 parts by weight of non-volatile components, from 3 to 75 parts by weight of imaging material and from 45 to 120 parts by weight of volatile solvent.

11. A non-stenciling, re-usable pressure-sensitive inkreleasing element comprising a flexible foundation, a continuous plastic film overlying said foundation as an adhesive middle layer to form the working surface of said foundation, and a top ink layer bonded to said working surface, said ink layer comprising the residue of a coating composition comprising a resin, a non-volatile component which is a non-solvent for said resin, imaging material and a volatile solvent for said resin which is also at least a partial solvent for said plastic of the middle layer, after evaporation of said solvent, said ink layer comprising as the continuous phase a porous, substantially non-pressure-transferable layer of said resin and containing as the discontinuous phase a pressure-transferable mixture of said non-volatile component and said imaging material, said ink layer being firmly bonded to the working surface of said foundation due to a partial dissolving of the plastic of said middle layer by the volatile solvent prior to evaporation.

12. A non-stenciling, re-usable pressure-sensitive inkreleasing element according to claim 11 in which the flexible foundation comprises a polyethylene terephthalate film and both the plastic of said adhesive middle layer and the resin of said top ink layer comprise vinyl resin.

13. A non-stenciling, re-usable pressure-sensitive inkreleasing ribbon according to claim 7 in which the resin comprises a vinyl resin and the non-volatile component comprises mineral oil.

14. A non-stenciling, re-usable pressure-sensitive inkreleasing element according to claim 11 in which the resin consists of a vinyl resin and the non-volatile, non-drying component comprises mineral oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,508,725 Newman May 23, 1950 2,810,661 Newman et al Oct. 22, 1957 2,820,717 Newman et a1. Ian. 21, 1958 2,893,890 Harvey July 7, 1959 2,944,037 Clark July 5, 1960 UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 3,037,879 June 5 1962 Douglas A. Newman et a1.

It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, lines 42 and 413 for "satisfatcory" read satisfactory column 4, line 46, for "bluish" read blush column 5 lines 3 to 5, the listing of the parts by weight, namely:

should be centered under the heading "Parts by weight" instead of as in the patent; column 5, lines 39 and 65, and column 6, lines 2 12, 23, 35 and 47, insert "Parts by weight" as a heading of the right-hand column in Examples 11, IV, V, VI, VII VIII and IX; column 8, lines 74 and 75, for "components" read component Signed and sealed this 25th day of September 1962.

' as, T'"

(SEAL) Attest: ERNEST W. SWIDER DAVID L. LADD Attesting Officer Gommissioner of Patents 

1. PROCESS OF PREPARING NON-STENCILING, RE-USABLE PRESSURE-SENSITIVE INK-RELEASING ELEMENTS WHICH COMPRISES COATING A FLEXIBLE FOUNDATION WITH AN OVERLAYER OF A CONTINUOUS PLASTIC FILM AS AN ADHESIVE MIDDLE LAYER TO FORM THE WORKING SURFACE OF SAID FOUNDATION, AND OVERCOATING SAID MIDDLE LAYER WITH A TOP LAYER OF RESINOUS COMPOSITION COMPRISING A RESIN, A NON-VOLATILE COMPONENT WHICH IS A NON-SOLVENT FOR THE RESIN, A VOLATILE COMPONENT WHICH IS A SOLVENT FOR SAID RESIN AND AT LEAST A PARTIAL SOLVENT FOR THE PLASTIC OF SAID MIDDLE LAYER, AND A QUANTITY OF IMAGING MATERIAL, AND ALLOWING SAID VOLATILE COMPONENT TO EVAPORATE WHEREBY IS FORMED A POROUS, SPONGY, INKRELEASING ELEMENT, SAID TOP LAYER BEING FORMLY BONDED TO THE WORKING SURFACE OF SAID FOUNDATION DUE TO A PARTIAL DISSOLVING THEREOF BY THE VOLATILE SOLVENT PRIOR TO EVAPORATION. 